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HABITAT USE AND POPULATION DENSITY OF PROBOSCIS MONKEYS (Nasalis larvatus) AT SAMUNSAM WILDLIFE
SANCTUARY, SARAWAK
Joshua Juan Anak. George Pandong
QL
Bachelor of Science with Honours P9 (Animal Resource Science and Management) J83
20052005
737
HABITAT USE AND POPULATION DENSITY OF PROBOSCIS MONKEYS (Nasalis larvatus) AT SAMUNSAM WILDLIFE SANCTUARY, SARA WAK
P.KHIDMATMAKLUMAT AKADEMIK UIiIMAS
111111111111" 11111111111 1000128293
JOSHUA JUAN AK. GEORGE PANDONG
This project is submitted in partial fulfilment of the requirements for the degree of Bachelor of Science with Honours
(Animal Resource Science and Management Programme)
Faculty of Resource Science and Technology UNIVERSITI MALAYSIA SARAWAK
2005
DECLARATION
No portion of the work referred to in this dissertation has been submitted in support of an application for another degree of qualification of this or any other university or institution of higher learning.
Joshua Juan ak. George Pandong
Animal Resource Science and Management Programme Faculty of Resource Science and Technology Universiti Malaysia Sarawak
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ACKNOWLEDGEMENT
First of all, I would like to thank Almighty God for His mercy and grace that sustained
me all my life. I would like to express my sincere gratitude and appreciation to Assoc. Prof.
Dr. Andrew Alek Tuen for his constant guidance, counsel, and supervision throughout the
completion of this thesis. Without his perseverance and leadership, the success of this thesis
would not be achieved.
I would also like to thank Sarawak Forestry Department for the penn it to carry out this
study at Samunsam Wildlife Sanctuary. I am also grateful to Sarawak Forestry Corporation
for providing free accommodation throughout this study. I would like to thank the wildlife
rangers of Samunsam Wildlife Sanctuary, Mr. Reming ak. Runyed and Mr. Jedel b. Hj. Mahli
for their valuable assistance and providing useful infonnation in this study. Not forgetting to
appreciate the efforts and willingness of Mr. Ali Ahmad b. Mat as the boat driver.
Additionally, this study was also supported with the help of Mr. Japri b. Senan and Mr.
Ridzuan b. Anuar as the guides.
Furthennore, I have been benefited through the special contributions from my peers
and colleagues whose support and advice does make a difference. Finally, I would like to
dedicate the success of this thesis to my parents, Mr. George Pandong and Mdm. Mary Giman
for their continuous prayers, support and encouragement throughout my endeavour.
This research was carried out under the UNIMAS Fundamental Research Grant no.
273/2002( 11).
III
TABLE OF CONTENTS
CONTENTS PAGE
Declaration ii
Acknowledgement iii
Table of Contents iv
List of Tables and Figures v
Abstract! Abstrak vi
1.0 Introduction 1
2.0 Literature Review 3
3.0 Materials and Methods 9
3.1 Study Site 9
3.2 Data Collection 11
3.2.1 Boat survey 11
3.3 Data analysis 12
4.0 Results 13
4.1 Comparison between August and November 2004 sightings of proboscis monkeys at Samunsam Wildlife Sanctuary, Sarawak 13
4.2 Summary of proboscis monkey's sightings for August and November 2004 14
4.3 Comparison between the types of habitat used by proboscis monkeys in August and November 2004 15
4.4 Population density of proboscis monkeys per kilometre (krn) surveyed 16
4.5 Results of Chi-square (i) test 17
4.6 Comparison of habitat characteristics between August and November 2004 18
5.0 Discussion 19
6.0 Conclusion and Recommendations 26
7.0 ferences 27
Appendices IV
LIST OF TABLES AND FIGURES
TABLES PAGE
The summary of proboscis monkey sightings, habitat use and group size for August and November 2004 14
2 The number of proboscis monkey groups using the different types of habitat in August and November 2004 15
3 Chi-square (i) test calculations of difference between no. of groups and individuals of proboscis monkeys sighted during August and November 2004 17
4 Habitat characteristics in August and November 2004 18
5 Comparison between the mean group densities (no. of group observed/ kIn surveyed) sighted along Samunsam River by Bennett & Sebastian (1988), Rubis (undated) and the present data (2004) 19
FIGURES PAGE
1 Distribution of forest types at Samunsam Wildlife Sanctuary, Sarawak (adapted from Bennett & Sebastian, 1988) 10
2 Map showing the start and end point of the boat survey conducted as well as sightings of proboscis monkeys in August and November 2004 13
3 Map showing the types of habitat along Samunsam River 15
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Habitat Use and Population Density of Proboscis Monkeys (Nasalis larvatus) at Samunsam Wildlife Sanctuary, Sarawak
Joshua Juan ak. George Pandong
Animal Resource Science and Management Programme Faculty of Resource Science and Technology
Universiti Malaysia Sarawak
ABSTRACT
A research was conducted at Samunsam Wildlife Sanctuary during the month of August and November 2004 to study the habitat use and population density of proboscis monkeys (Nasalis larvatus). Results indicated that there were distinct differences in the range of habitat use between August and November 2004 with the abrupt expansion from 0.5 km in the month of August to 3 km of different habitat types used in November. The major type of habitat utilized by proboscis monkeys was the mangrove forest. A mixture of mangrove, mixed dipterocarp and tropical heath forest were also used during both seasons. Towards November 2004, the tropical heath-riverine forest habitat was utilized as a result of higher availability of young leaves during this season. Comparison of proboscis monkey density sightings between August and November 2004 showed a distinct difference with only 0.08 groups/ km surveyed in August compared with 0.27 groups/ km surveyed during November 2004. Sightings of individual density showed 0.48 individuals/ km surveyed in the month of August whereas 1.34 individuals/ km surveyed in November 2004. Chi-square (l) test was calculated and showed that there were significant differences (p < 0.05) between both seasons in the no. of group and individual sighted. Sightings of proboscis monkeys were probably influenced by food availability and competition for food resources.
Key words: Nasalis larvatus, Samunsam Wildlife Sanctuary, habitat use, population density, food availability.
A BSTRAK
Sebuah kajian telah dijalankan di Sanktuari Hidupan Liar Samunsam pada bulan Ogos dan November 2004 untuk mengkaji penggunaan habitat dan kipadatan populasi orang belanda (!iasa/is larvatus). Keputusan menunjukkan terdapat perbezaan yang ketara dalam julat penggunaan habitat antara Ogos dan November 2004 dengan peluasan secara mendadak daripada 0.5 km pada bulan Ogos kepada 3 km habitat yang pelbagaijenis pada bulan November. Jenis habitat utama yang digunakan oleh orang belanda adalah hutan paya bakau. Suatu campuran hutan paya bakau, dipterokarp campuran dan kerangas tropika turut digunakan pada kedua-dua musim. Menuju November 2004, habitat hutan kerangas tropika-persisiran sungai digunakan hasil daripada keberadaan daun muda yang lebih tinggi pada musim ini. Perbandingan antara kepadatan kumpulan orang belanda yang diperhatikan antara Ogos dan November 2004 menunjukkan perbezaan yang ke/ara dengan hanya 0.08 kumpulan/ km pemantauan ketika bulan Ogos dibandingkan dengan 0.27 kumpulan/ km pemantauan ketika bl/lan November 2004. Pemerhatian kepadatan individu menunjukkan 0.48 individul km pemantauan pada bulan Ogos yang mana 1.34 individul km pemantauan pada November 2004. Ujian Chi-kuasa dua (l) telah dikira dan menunjukkan bahawa terdapat perbezaan yang signifikan (p < 0.05) antara kedua-dua musim dalam bi/angan kumpulan dan individu yang diperha/ikan. Pemerhatian orang belanda kemungkinan dipengaruhi oleh keberadaan makanan dan persaingan un/uk sumber makanan.
Kala kunci: Nasalis larvatus, Sanktuari Hidupan Liar Samunsam, penggunaan habitat, kepadatan populasi, keberadaan makanan.
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1.0 INTRODUCTION
Proboscis monkeys (Nasalis larvatus) can only be found in the island of Borneo, but
they do not live throughout the island. They are only limited mainly to coastal swamp forests
and to fOIests next to large rivers. These coastal swamp forests mainly consist of mangrove
and peat swamp forests (Bennett & Gombek, 1993). However, it is unwise to assume that
probo cis monkeys occupy any area of mangrove or peat swamp forest. Their habitat depends
on the different zones where different types of trees are used for foraging or sleeping. Small
numbers are sometimes found further inland next to major rivers. This is because they are
likely to live in forests that grow on nutrient-rich alluvial soils such as mangroves or alongside
rivers where sufficient supply of digestive food are available (Bennett & Gombek, 1993).
The pattern of daily habitat use is determined by two main factors, which are the
location of good food sources and rivers. Proboscis monkeys return to their trees next to the
river every single night (Bennett & Gombek, 1993). Trees used for sleeping are generally tall
and fairly open for better visibility. This is presumably allows the animals to stay alert for
predators as well as to provide a good view of the best places for foraging in the morning.
After dawn, they will move from their sleeping habitats to forage into the forest away from
the river. Their food is often scarce and scattered; therefore, they need to travel much further
in long distances to find enough food sources to survive. Therefore, much of their activity
time will be spent alternating between feeding, resting and travelling (Bennett & Gombek,
1993).
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Despite their endemic status, proboscis monkeys are facing pressures as a result of
illegal hunting and loss of their habitat caused by humans (Rubis, 2001). Research proves that
proboscis monkeys do not generally do well in captivity. They are extremely selective feeders
and because of poor captive diets, their delicate digestive system would be stressed and this
would eyentually result in death (Bennett & Gombek, 1993). Therefore, with the alarming
threats and ineffectiveness of ex-situ conservation measures, proboscis monkeys must be
protected with in-situ approach.
Most researches carried out at Samunsam Wildlife Sanctuary were done back in the
mid-1980s and early 1990s (e.g. Bennett & Sebastian, 1988). The latest research was
conducted by Rubis from October 200.1 to September 2002 (Rubis, undated). Based on Rubis '
works, the pressures posed by humans were the main reason of the population decline. The
decline may have influenced their habitat use between then and now. Moreover, if habitat
characteristics of the proboscis monkeys have changed in recent years, then it may affect their
behaviour as well. Thus, data collected through this research can be used to compare with data
from similar studies done by other researchers as well as updating observation data done by
Rubis.
The present study is initiated in order to determine the habitat use by proboscis
monkeys during August and November 2004 and to estimate the population density sighted
along Samunsam River. This is carried out in order to support and revise the current
information available at Samunsam Wildlife Sanctuary, as well as to provide basic
information, which is useful for the in-situ conservation of proboscis monkeys.
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,..... I
2.0 LITERATURE REVIEW
The study area for this research is at Samunsam Wildlife Sanctuary. Samunsam is the
oldest wildlife sanctuary in Sarawak and is located at the western tip of Sarawak (10 78' N,
109 0 36' E) (Bennett & Sebastian, 1988). In 1979, it was gazetted with the fundamental
objective of protecting proboscis monkeys and they are probably the largest known protected
population in Sarawak, with approximately 150 individuals (Rubis, undated).
Most researches on proboscis monkeys in Samunsam Wildlife Sanctuary were done
during the mid-1980s and early-1990s. Among them are Bennett & Sebastian (1988),
Rajanathan & Bennett (1990), Bennett & Gombek (1993), Bennett & Davies (1994), Rubis
(2001 & undated) and their associates. There are other researchers who had done their study
on proboscis monkey throughout the island of Borneo. Among them are Yeager (1989 &
1995) and Yeager et al. (1997) who conducted their research at Tanjung Puting National Park,
Kalimantan Tengah, Indonesia and Boonratana & Sharma (1992) as well as Boonratana
(2000) who conducted a few studies in the Lower Kinabatangan, Sabah. Although their
research may not be similar in terms of study sites, study discipline, objectives and
methodology, yet the information that they had provided has been a great contribution to other
subsequent studies, such as in the field of habitat utilization.
According to Salter et al. (1985), habitat use refers to the preferred habitat to be used
significantly for feeding, moving, resting and other related activities. Therefore, in the present
stu , habitat use by proboscis monkeys observed includes the sleeping location, foraging
sites and food-related travel activities.
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I
Among the first research done on proboscis monkeys in Sarawak that includes
amunsam Wildlife Sanctuary was carried out by Salter et al. (1985). They found out that
groups of proboscis monkeys were recorded in a variety of riparian and coastal habitats. Areas
around human settlements were completely avoided, although some were seen to use
electively felled tidal forests, remnant tidal forests adjacent to agricultural land and logged
high forest. Salter et al. (1985) also reported that the proboscis monkeys slept primarily along
river edges, moving inland up to 750 m during the day and returning to the riverside in late
afternoon. They also observed proboscis monkeys feed on at least 90 plant species, including
leaves or shoots, fruits, seeds and flowers.
The research done by Bennett & Sebastian (1988) and Bennett & Davies (1994) found
out that N. larvatus were highly selective feeders, travelling directly between food sources,
even if they were widely spaced. They were also being selective with the food that they eat
prefering young leaves, fruit stalks and seeds of certain plants.
The minimum average day-range of proboscis monkeys is more than 706 m as the
distance observed is only between sleeping sites (Bennett & Davies, 1994), thus, the actual
average day range is likely to be much longer (up to 2000 m). Their home-range area was
estimated to be 900 ha at Samunsam. However, the population density and biomass of
proboscis monkeys in Samunsam was low (0.52 group/ km2 and 46 kg! krn2) compared to
other colobine monkeys, such as Presby tis rubicunda at Sepilok, Sabah that has a population
de sity of2.7 groups/ km2 and a biomass of 49 kg/ krn2 . Illegal hunting was assumed to be the
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rea on for the low population density and their wide-ranging behaviour were an indication
that food availability was low at coastal forests (Bennett & Sebastian, 1988).
Another research was done on the study of social behaviour of proboscis monkeys at
Samunsam Wildlife Sanctuary by Rajanathan & Bennett (1990). The study found out that all
mixed-sex groups were harems with the average group size of nine. All-male groups were also
recorded. However, in terms of spatial distance, harems were spatially cohesive than the more
scattered all-male groups. They also noted that harems change their composition frequently,
with both females and males switching between groups. Other observations include group
movements which were observed to be led by the females and not the male.
In Boonratana & Sharma's (1992) research, they observed population of proboscis
monkeys to be at least 750-830 individuals during 1990 and 1991. The main group at Sukau
used an area more than 220 ha and travelled at least 600 m away from the Kinabatangan and
Menanggul Rivers in search of food . However, it was observed that much larger area that was
used as full-day tracks were unsuccessful.
Boonratana & Sharma (1992) encountered many setbacks in conservation measures
taken around their study areas. Among the major setback was proboscis monkeys protected in
a particular area were found outside the reserve.
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Boonratana (2000) made a follow up on his research and made some interesting
findings. The result of the research shows that a negative correlation existed between
vigilance and day range length. There were also no daily correlations between vigilance
activity and food items in the diet. However, there was a significant positive correlation
between vigilance and flowers in diet. This proposes that proboscis monkeys in a one-male
group (SU I) increased their vigilance to locate rare food items. The opposite result was shown
between vigilance and fruits (including seeds) in the diet. Boonratana (2000) suggested "they
spent less time at vigilance when there were more fruits in their diet, probably to maximise
feeding on rare food items". Boonratana (2000) also found out that members of one-male
group in Sukau spent approximately 27.8% of their annual activity budget in vigilance while
members at Abai study area spent 30%.
Yeager (1989) provided information on the feeding ecology of proboscis monkeys at
Natai Lengkuas Station, Tanjung Puting National Park, Kalimantan Tengah Indonesia. She
found out that proboscis monkeys utilizes 55 different plant species, of which the three most
important species used were Eugenia sp., Ganua motleyana and Lophopetalum javanicum.
However, Yeager (1989) also recorded that proboscis monkeys were selective feeders and do
not feed simply based on relative density. They tend to switch dietary strategies and increased
dietary diversity during times of low food abundance. Other observations by Yeager (1989)
include the total home range was estimated to be 130.3 ha, an average group density of 5.2
groups per km2 and the average biomass per km2 was estimated to be 499.5 kg at Natai
Lengkuas.
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On the other hand, Yeager et at. (1997) provided much detailed research on diet and
foliage selection of proboscis monkeys. Samples were collected and analyzed on two different
periods in the year 1985 and 1992 at Tanjung Putting National Park. Their research proved
that diet selection was not only based on the relative availability of food items but also in its
quality. Jt was found that leaves consumed by proboscis monkeys are relatively higher in
protei n, lower in fibre and contain significantly higher concentrations of phosphorus and
potassium.
Another study conducted by Nijboer et at. (undated) further explained the functions
and purposes as to why proboscis monkeys and other colobines prefer this type of diet.
According to Nijboer et at (undated), apart from sustaining normal digestive physiology, it is
a necessity to provide "a suitable diet for ' supporting pregastric fermentation for microbial
degradation of plant cell wall constituents as an energy source". In return, suitable microbial
populations contribute important detoxification mechanisms for coping with secondary
compounds identified in leaves and seeds consumed in nature. They also added "both
excessive soluble carbohydrates and protein concentrations in diets fed to captive colobines
have implicated in health disorders".
Rubis (undated) conducted a more recent study during the period of October 2001 till
September 2002 at Samunsam Wildlife Sanctuary to estimate current primate abundance.
Preliminary report from the observation shows surprising and alarming results. Even with
high abundance of food supply, proboscis monkeys were observed actively foraging in mixed
dip' 'rocarp secondary forests (behind the sanctuary's headquarters), which are habitats where
no earll r presence was recorded in the sanctuary (Rubis, 2001).
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Rubis (2001) stated that proboscis monkeys rarely spend the night on riverbanks in
recent time period. Furthermore, Rubis observed that fewer groups of proboscis monkeys
have been observed by the river during evening counts compared to ten years ago. The change
of behaviour may well be the results of more illegal human activities such as land clearing and
illegal hunting. This poses a very alarming threat that would potentially influence population
density. Therefore, proboscis monkeys may travel further inland to ensure their safety and
provide extra protection from poachers (Rubis, undated).
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3.0 MATERIALS AND METHODS
3.1 Study Site
.Samunsam Wildlife Sanctuary has a wide range of habitats. The four main forest types
in the area are mangrove, riverine, mixed dipterocarp and tropical heath forest (Bennett &
Sebastian, 1988) (see Fig. 1).
Mangrove forest covers about 5 kIn upriver along the lower reaches of Samunsam
River (Rubis, 2001). Rhizophora sp. is the dominant plant species with patches of common
mangrove trees that include Avicennia sp. and Sonneratia sp. can be seen growing by the
riverbanks. These in turn are replaced by Bruguiera sp. and nip a palms (Nypa fruticans)
towards upper reaches to form a mangrove-nip a forest, approximately 4-6 kIn from the mouth
of the river (Bennett & Sebastian, 1988).
Riverine forest spreads mainly along the upper reaches of the Samunsam River (Rubis,
2001 ). The forest occurs patchily throughout the area and consists of Shorea sp., Vatica sp.,
Eugenia sp. and Tristania sp. as the common tree genera (Bennett & Sebastian, 1988). Rattans
(Calamus sp.) are abundant at the usually dense undergrowth. Clusters of nibong palms
(Onco cperma tigillarium) are also found in riverine forest along Samunsam River (Rubis,
2001).
9
[] --- -"1
i
t I A
SEA
Fig. 1. Distribution of forest types at Samunsam Wildlife Sanctuary, Sarawak (adapted from Bennett & Sebastian, 1988)
Tropical heath forest is the mos,t widespread forest type as it covers area away from i
the shore and rivers (Bennett & Sebastian, 1988). However, it does occur in patches with
other forest types along Samunsam River. Among the common tree genera found in this type
of forest are Shorea sp. and Palaquium sp. The trees grow on soil that consists of a thick layer
of grey-humus stained sand underlying a layer of quartz sand (Rubis, 200 1).
Mixed dipterocarp forest has the most diverse plant species of all the forest types in
the sanctuary and consists of tall, broad and heavily buttressed trees (Rubis, 2001). Among the
common tree families include Dipterocarpaceae, Euphorbiaceae, Moraceae, Sapotaceae and
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Anacardiaceae. Common tree genera include Shorea sp., Artocarpus sp. and Aporusa sp. with
a variety of non-climbing and climbing palms are also present in this forest (Rubis, 2001).
3.2 Data Collection
Data for this study were collected at two different periods, which is during the dry and
wet season. The first data collection was carried out on 8th_l i h August 2004 to represent dry
season data while the second data collection was carried out on 3rd - i h November 2004 to
represent the wet season data. Data collection was mainly done by boat surveys. This method
provided infonnation on the comparison between proboscis monkey sightings, comparison
between habitat types used by proboscis monkeys, density of proboscis monkeys as well as
habitat characteristics comparison.
3.2.1 Boat Survey
Boat surveys were done along the Samunsam River and timed carefully at
dawn (5:30am - 7.30am) and dusk (6:30pm - 8:30pm) to observe the proboscis
monkey sleeping sites. When there was a proboscis monkey sighting, the boat was
slowed down to a halt. This was to enable observation done using binoculars and the
naked eye on the group size, observed number of adult, juvenile, male and female in
the group. The characteristics of habitat used by proboscis monkeys were also
recorded. Characteristics include habitat types, types of terrain (e.g. hilly, flooded, flat
or swamp etc), plant species used, and height of plants (above ground). A mobile GPS
unit, Gannin eTrex™ Vista was used to record the position of proboscis monkeys.
Other relevant observations were also noted down.
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3.3 Data analysis
Analysis of data was done on the density of proboscis monkeys sighted per kilometre.
The fonnulas used were as below:
· Total no. oJ groups sighted Group denslly = -------=---=-~-~-
Total km surveyed
··d I d . Total no. oJ individuals sighted IndlVl ua enslty =------..::------=-
Total km surveyed
Total km surveyed = Length oj river transect surveyed (km) x Frequency oj boat surveys
Besides that, Chi-square (X2) test was also calculated to compare the frequency of
j
proboscis monkey sightings between August (dry season) and November (wet season) 2004.
The fonnula and hypotheses used are as below:
2x 2 =L (Observed - Expected) Expected
Ho= There is no difference between no. of groups or individuals of proboscis monkeys sighted
during both seasons
Ha= There is a difference between no. of groups or individuals of proboscis monkeys sighted
during both seasons
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4.0 RESULTS
4.1 Comparison between August and November 2004 sightings of proboscis monkeys
at Samunsam Wildlife Sanctuary, Sarawak
Referring to Figure 1, there were distinct differences between the range of habitat use
between August and November 2004. In August, there was only about 0.5 km of habitat use
compared to a range of 3 km in November.
I I
I
Legend: • Proboscis monkeys sighted in August 2004 • Proboscis monkeys sighted in November 2004
Fig. 2. Map showing the start and end point of the boat survey conducted as well as sightings of proboscis monkeys in Aug. and Nov. 2004
13
4.2 Summary of proboscis monkey sightings for August and November 2004
There were a total of six boat surveys conducted for each trip during August and
November 2004. The information from the boat surveys is summarized in Table I.
Table 1. The summary of proboscis monkey sightings, habitat use and group size for August and November 2004
SIGHTINGS HABITAT USE GROUP SIZE Month 1(2004)
... <Il
=~ = <
... ~ ~
e ~, 0 Z
Group Type of Side of Tree(s) used for Approx. (J ~ Juve.Label habitat river sleeping height
Al MF Left Rhizophora sp. 9-12 m I 4 -A2 MF Left Avicennia sp. S-9 m I I 2 -A3 MF Left Rhizophora sp. 6-10 m I ~S N.D. A4 M+MD+THF Right Casuarinaceae 10-IS m I 4 2
Total:
NI MF Left Casuarinaceae 12-IS m I 2 -N2 MF Left Rhizophora sp. 12-IS m 3 N.D. N.D. N3 TH+RF Right Casuarinaceae I O-IS m 3 N.D. N.D. N4 MF Left Rhizophora sp. 12-IS m I 2 I NS M+MD+THF Right Casuarinaceae IS-20 m 1 3 1 N6 M+MD+THF Right Dipterocarpus sp. IS-20 m 1 2 1 N7 TH+RF Right N.D. 17-20 m I 3 2 N8 TH+RF Right . N.D. IS-20 m 3 2 -N9 MF Left I Rhizophora sp. 12-1S m I - -NIO MF Left I Avicennia sp. S-9 m I - -NI J M+MD+THF Right Dipterocarpus sp. IS-20 m I 3 2 NI2 MF Left Rhizophora sp. 9-12 m I - 2 -NI3 MF Left Rhizophora sp. 12-IS m 2 3 2 NI4 TH+RF Left Casuarinaceae I0-IS m I 2 I
Total:
Tota
S 3 10 7
2S
3 12 10 4 S 4 6 S I I 6 2 7 4
70
I
MF = Mangrove forest M+MD+THF = Mangrove + Mixed dipterocarp + Tropical heath forest TH+RF = Tropical heath + Riverine forest N.D. = Not determined
14
Pusat Khidmat Maklumat Akade' UNIVERSITI MALAYSiA SARAW
94100 KOla Samarahan
4.3 Comparison between the types of habitat used by proboscis monkeys in August
and November 2004
There are four main types of habitat along Samunsam River (see Figure 3 and Table
2). Some of the habitats are a mixture of different forest with patches of common tree genera
seen growing along with other trees from different types of habitat (refer to 3.0 Study Site for
further details of forest types).
/ " /
/ '"
Legead:
- ~flDgrove fom! - M1oxrovc +Mixed dipttl'OCll'p +Tropical hudl fomt - MIDgron +Nipi femt - Tropkal beatil +RinriDf foreA
Fig. 3. Map showing the types ofhabitat along Samunsam River
Table 2. The number of proboscis monkey groups using the different types of habitat in Aug. and Nov. 2004
No. of groups in: Aug. 2004
3
Nov. 2004 I
7 Types of habitat Mangrove forest Mangrove + Nipa forest 0 0 Mangrove + Mixed dipterocarp + Tropical heath forest 1 3 Tropical heath + Riverine forest 0 I 4
Total no. of groups: 4 I 14
15
4.4 Population density of proboscis monkeys per kilometre (km) surveyed
a. August 2004
Total length of river surveyed = 8.72 km
Total no. of boat surveys = 6
No. of group sighted = 4
No. of individual = 25
Group density = ( __4_) =0.08 groups / km surveyed 8.72 x 6
Individual density = ( 25 ) = 0.48 individuals / Ian surveyed8.72 x 6
b. November 2004
Total length of river surveyed = 8.72 km
Total no. of boat surveys = 6
No. of group sighted = 14
No. of individuals sighted = 70
Group density = ( 14 ) =0.27 groups / km surveyed 8.72x 6
Individual density = ( 70 ) =1.3379 individuals / km surveyed 8.72x 6
16
4.5 Results of Chi-square ('i) test
Chi-square (xh test was used to compare the sighting frequency between August and
November 2004.
Table 3. Chi-square (xh test calculations of difference between no. of groups and individuals of proboscis monkeys sighted during Aug. and Nov. 2004
~ONTHS(SEASON)2004
August (dry) November (wet) SIGNIFICANCE
No. of groups: 4 14 p < 0.05
No. of individuals: 25 70 p < 0.05
Chi-square (-I) test showed that there was a significant difference between dry and wet
season in the no. of groups and no. of individuals of proboscis monkeys sighted along
Samunsam River. Therefore, we reject the null hypothesis (Ho) and accept the alternative
hypothesis (Ha).
17